STUDIES IN IDAHO 



20I 



on the other hand, 8.8 per cent and 14.8 per cent were killed each 

 year on the lightly and the heavily grazed areas, respectively. 

 As was to be expected, during the first few years of growth the 

 seedlings were readily killed by only slight injuries. This was 

 because of their small size, the shallow root system, and the 

 presence of only a small amount of woody material in their stems. 



Comparative Seasonal Injury. — The percentage of seedlings 

 killed by grazing, notably those less than one year old, was appre- 

 ciably greater early in the 5 

 season than it was later. 

 Early in the season, when 

 the soil is wet, the roots are 

 readily trampled out of the 

 ground, and the stems are 

 easily crushed or torn asun- 

 der by the sharp, cutting 

 hoofs of the sheep. To- 

 wards the end of the season 

 the stems are much tougher, 

 the roots are deeper, and 

 the soil is firmer; hence the 

 injury is usually much less 

 serious than in the spring. 

 In general, however, there 

 is a sufficient number of 

 seedlings left on the mod- 

 erately grazed lands follow- 

 ing a good seed year to 

 make a full stand of timber 

 in spite of the injuries caused 

 by stock. Accordingly, where the stock are carefully handled, a 

 satisfactory stand of reproduction may be expected on practi- 

 cally all lands in the Northwest. 



Damage According to Intensity of Grazing and Amount of 

 Forage. — Generally, the amount of injury or actual destruction 

 of the reproduction increases with the closeness of the grazing 

 (Fig. 65). Except on bed grounds and trails the damage was 



{Forest Service.) 

 Fig. 65. — A YELLOW PINE 4 FEET TALL, 

 WITH LATERAL BRANCHES SEVERELY 

 BROWSED BY SHEEP ON OVERGRAZED 

 RANGE. 



The leader is out of reach of the sheep, and this 

 makes possible the entire recovery of the sap- 

 ling if destructive grazing is discontinued. 



